1. Technical Field
The present disclosure relates to a selectable one-way clutch.
2. Description of Related Art
As one-way clutches, there have been known selectable one-way clutches capable of switching states of struts (engagement pieces) of pocket plates and notches (engagement recesses) of notch plates between an engagement state and a non-engagement state through selector plates disposed between the pocket plates and notch plates. In such selectable one-way clutches, the selector plates relatively slide against the pocket plates or the notch plates; therefore, a lubricating oil is supplied to sliding surfaces among these plates so as to secure a smooth movement among the components.
For example, in Japanese Patent Application Publication No. 2003-021220, there is proposed an apparatus configured such that, in a stator used in a torque converter of an automatic transmission or the like, recesses and oil passages communicating with the respective recesses are formed in a surface of a stator body that faces a notch plate, thereby supplying the lubricating oil to the sliding surfaces of the stator body and the notch plate.
The respective plates of the selectable one-way clutch are configured to be rotated relative to each other; therefore, for example, if the notch plate is rotated relative to the fixed pocket plate, torque is applied via the lubricating oil onto the selector plate disposed between the pocket plate and the notch plate. Such a torque is a dragging action caused by a shear force derived from viscosity of the lubricating oil, and a greater torque (dragging torque) acts as the viscosity of the lubricating oil becomes higher.
A common selectable one-way clutch is configured such that an arm is coupled to a selector plate, and the arm is moved by an actuator including a return spring so as to carry out switching between the engagement state and the non-engagement state. For example, no torque is required to be transmitted before an engine start up, and thus the arm is held to be urged by an elastic force of the return spring in a manner as to put the pocket plate and the notch plate in the non-engagement state.